Command entry:
Create panel 
(Helpers)
Object Type rollout
Crowd
Setup rollout
Behaviors group
Click the New button.
Select Behavior Type dialog
Scripted Behavior
The Scripted behavior lets you create custom behaviors using MAXScript. A scripted behavior can incorporate one of three behavior types: Force, Constraint, or Orientation.
For detailed information on scripting behaviors, see the MAXScript Help, available from the Help menu.